<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>实战1</title>
</head>
<body>
    <script>
        let sum = 0;
        for(let i = 1; i <= 100; i++){
            sum += i;
            // console.log(sum,i);
        }
        alert(sum);
    </script>
</body>
</html>